Abstract: Migraine aura is a sometimes disabling disorder of the brain that involves significant neurological symptoms in about 30% of patients. In this issue of Neuron, van den Maagdenberg et al. characterize a mouse with a knockin mutation known to cause familial hemiplegic migraine and provide evidence that a lowered threshold to the triggering of CSD may account for the devastating phenotype of familial hemiplegic migraine.